Flexure hinge assembly

ABSTRACT

A flexure hinge assembly wherein a pair of fixed telescoped tubular members are provided, each having one or more pairs of axially spaced slots extending through their walls, the ends of one slot of each pair terminating a predetermined circumferential distance from the corresponding ends of the other slot of the same pair to form at least two flexure portions between the ends. The flexure portions of one of the tubular members extend parallel to the axes of the members, and the flexure portions of the other tubular member extend perpendicular to the axes of the members. A method of manufacturing a flexure hinge assembly.

United States Patent Bilinski et al.

[541 FLEXURE HINGE ASSEMBLY [72] Inventors: Donald J. Bilinski, RandolphTownship, Dover County, N.J.; Leon Weisbord, New York, N.Y.

[73] Assignee: The Singer Company, New York,

22 Filed: April 15, 1970 21 Appl. No.: 28,592

[52] US. Cl ..308/2 A, 74/5 F, 287/85 [51] Int. Cl. ..Fl6c 11/12, G01c19/18 [58] Field of Search ..308/2 A; 74/5; 248/358; 64/11, 64/15;287/85 [56] References Cited UNITED STATES PATENTS 3,575,475 4/1971Boerner ..74/5

3,585,866 6/1971 Ensinger ..74/5

2,960,302 11/1960 Brown ..74/5 X 3,301,073 1/1967 Howe ..74/5 X2,937,053 5/1960 Rigney ..308/2 A 1 Oct. 24, 1972 PrimaryExaminer-Manuel A. A'ntonakas Attorney-S. A. Giarratana, Thomas W.Kennedy and S. Michael Bender [57 ABSTRACT A flexure hinge assemblywherein a pair of fixed telescoped tubular members are provided, eachhaving one or more pairs of axially spaced slots extending through theirwalls, the ends of one slot of each pair terminating a predeterminedcircumferential distance from the corresponding ends of the other slotof the same pair to form at least two flexure portions between the ends.The flexure portions of one of the tubular members extend parallel tothe axes of the members, and the flexure portions of the other tubularmember extend perpendicular to the axes of the members. A method ofmanufacturing a flexure hinge assembly.

6 Claims, 11 Drawing Figures Patehted Oct. 24, .1972 3,700,289

5 Sheets-Sheet 1 FIG. 1%

IAVVEIVTOJVQS:

DONALD J. BILIINSKI BY LEON WE/SBORD XQW ATTORNEYS Patented l Oct. 24,,1972 I 3,700,289

5 Sheets-Sheet 5 w INVENTOR DONALD J. BILINSKI a LEON. WEISBORD ATTORNPatented Oct. 24,1972 7 3,700,289

r 5 Sheets-Sheet 4 |26:|56 INVENTOR DONALD J. BILINSKI 8:

LEON WEISBORD ATTORNEY 5 Sheets-Sheet v 5 FIG.

- INVENTOR DONALDkl-BILINSKI a LEON WEISBORD FLEXURE HINGE ASSEMBLYBACKGROUND OF THE INVENTION This invention relates to a flexure hingeassembly, and, more particularly, to such an assembly for connecting tworotary members while permitting universal movement between them.

Several proposals have been made for a flexure joint extending between adriven member, such as a flywheel, or the like, and its drive shaft, sothat the former may be rotationally torqued by the latter, and yet beessentially free of spring restraints for a predetermined range ofangular deflections between the two members. For example, in U.S. Pat.No. 3,354,726, by W. J. Krupick and R. F. Cimera, and as signed to theassignee of the present invention, an inner hinge unit is concentrallydisposed within an outer hinge unit, with the assembly thus formedhaving two pair of oppositely disposed flexure bars which permituniversal tilting between the upper portion and the lower portion of theassembly. One of the hinge units has its flexure bars oriented in amanner to contribute high axial strength along the spin axis of theflywheel, and the other unit has its flexure bars positioned so as toprovide the necessary radial and torsional stiffness. However, duringmanufacture of the assembly, the thin flexure sections in each unit areformed by machining four equally spaced pair of separated blind holes inthe outside walls of a hollow cylindrical work piece. The work piece isdivided into three gimbal portions while making appropriately shapedslots in the wall of the assembly thus formed, thus freeing each gimbalfor angular displacement about its respective flexure axis. However,this cutting of the blind holes is extremely difficult, especially dueto the fact that the delicate thin flexure sections in each hinge unitare easily ruptured, or overstressed, during assembly since no limitstops are provided to restrict the angular displacement of therespective gimbals. Therefore, due to the machining of these blindholes, it is necessary to position the inner and outer hinge units byresorting to the use of external reference surfaces. As a result, slightmisalignment in the flexure axes of the two hinge units frequentlyoccurs in production, leading to the introduction of excessive andunsymmetrical spring rates in the finished gyroscope. Further, theformation of the flexure bars in the above manner results in the latterhaving a nonuniform thickness across their respective bending axes,leading to further anormalization in the hinge assembly spring rates.

SUMMARY OF THE INVENTION It is, therefore, an object of the presentinvention to provide an improved gyroscope flexure hinge assembly whichmay be manufactured in a simpler manner than the prior art hingeassemblies, yet with greater accuracy of finish.

Towards the fulfillment of this object, the flexure hinge assembly ofthe present invention comprises a flexure hinge assembly comprising apair of fixed telescoped tubular members, each having at least two pairsof slots extending through the wall thereof, the slots of one pair beingaxially spaced from the slots of the other pair to form at least threegimbal portions in each member, the ends of one slot of each pair of oneof said members terminating a predetermined circumferential distancefrom the corresponding ends of the other slot of the same pair to format least two flexure portions between said ends, said flexure portionsextending parallel to the axes of said members, the ends of one slot ofeach pair of the other of said members terminating a predetermined axialdistance from the corresponding ends of the other slot of the same pairto form at least two additional flexure portions between said ends, saidadditional flexure portions extending perpendicular to said axes.

BRIEF DESCRIPTION OF THE DRAWINGS Reference is now made to theaccompanying drawings for a better understanding of the nature andobjects of the present invention. The drawings illustrate the best modepresently contemplated for carrying out the objects of the invention andare not to be construed as restrictions or limitations on its scope. Inthe drawings:

FIG. 1 is an enlarged exploded perspective view depicting the hingemembers which together make up the hinge assembly of the presentinvention;

FIGS. 2 and 3 are developed views, depicting the inner hinge unit andthe outer hinge unit, respectively;

FIGS. 4 and 5 are a front elevational view, and a side elevational view,respectively, depicting the assembled hinge assembly of the presentinvention;

FIGS. 6-10 are views similar to FIGS. l-5, respectively, but depictinganother embodiment of the present invention; and

FIG. 11 is a perspective view of the assembly of FIGS. 6-10 along with acutter tool utilized in the manufacture of the assembly.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring specifically to FIGS.1-3 of the drawings, the flexure hinge assembly of the present inventionincludes an inner hinge unit 10 and an outer hinge unit 40. Although theunits 10 and 40 are shown axially separated in FIG. 1 for theconvenience of presentation, they are normally telescoped, one withinthe other in a concentric manner about a principal axis Z.

As shown in FIGS. 1 and 2, the inner hinge unit 10 is in the form of aright circular cylinder, or tubular member, having a central bore 12 anda pair of generally circumferential extending slots 14 and 16. Theseslots are generally U-shaped, as better shown in FIG. 2, and anenlarged, radially extending bore, of a diameter exceeding the width ofthe slots, is formed at the ends of each slot. In particular, bores 14aand 14b are formed at the ends of the slot 14, and bores 16a and 1617are formed at the ends of the slot 16. The bores 14b and 16a are spacedapart slightly to form a neckeddown flexure portion 18, and the bores16b and 14a are spaced slightly apart to form a necked-down flexureportion 20, the flexure portions 18 and 20 extending parallel to theaxis 2.

An additional pair of slots 24 and 26 are formed through the inner hingemember 10 in an axially spaced relation to the slots 14 and 16. Theslots 24 and 26 are also generally U-shaped, are inverted with respectto the slots 14 and 16, and each has a bore formed at its ends. Inparticular, bores 24a and 24b are formed at the ends of the slot 24,while bores 26a and 26b are formed at the ends of the slot 26. The bores24b and 26a are spaced slightly apart to form a necked-down flexureportion 28, and the bores 26b and 24a are spaced slightly apart to forma necked-down flexure portion 30. As in the case of the flexure portions18 and 20, the flexure portions 28 and 30 extend parallel to the axis Z.

It is noted from an inspection of FIG. 2 that the flexure portions 18,20, 28 and 30 are spaced at 90 intervals around the circumference of theinner hinge unit 10, with the slot 14 overlapping the flexure portion28, the slot 16 overlapping the flexure portion 30, the slot 24overlapping the flexure portion 20, and the slot 26 overlapping theflexure portion 18.

In this manner, three gimbal portions 32, 34 and 36 are formed as aresult of the above slots, with the flexure portions 18, 20 28 and 30permitting flexing between the middle gimbal portion 34 with respect toeach of the other gimbal portions 32 and 36, while providing strength inthe axial direction of the unit 10.

The outer hinge unit 40 is shown in FIGS. 1 and 3, and is similar to theinner hinge unit with the exception that the flexure portions formed inconnection with the former extend in a direction perpendicular to theaxis Z. Particularly, a pair of slots 44 and 46 are provided through thewall of the unit 40, are generally U-shaped and have bores 44a, 44b, and46a, 46b, respectively, formed at the ends thereof. The bores 44b and46a are spaced apart in the axial direction of the unit to define aflexure portion 48, and the bores 46b and 44a are spaced apart in thesame direction to define a flexure portion 50.

An additional pair of slots 54 and 56 are formed through the hinge unit40 and are axially spaced from the slots 44 and 46. These slots are alsogenerally U- shaped and are inverted with respect to the slots 44 and46. Bores 54a and 54b are formed at the ends of the slot 54, and bores56a and 56b are formed at the ends of the slot 56, the bores 56a and 54bbeing spaced apart in the axial direction of the unit to define aflexure portion 58, and the bores 54a and 56b being spaced apart in thesame direction to define a flexure portion 60. The flexure portions 48,50, 58 and 60 thus extend in a direction perpendicular to the axis Z.

As in the case of the unit 10, the flexure portions 48, 50, 58' and 60are spaced apart at 90 intervals, and the slot 44 overlaps the flexureportion 58, the slot 46 overlaps the flexure portion 60, the slot 54overlaps the flexure portion 50, and the slot 56 overlaps the flexureportion 48.

Three gimbal portions 62, 64 and 66 are formed by the slots 44, 46, 54and 56, and the flexure portions 48, 50, 58 and 60 permit relativeflexing movement between the middle gimbal portion 64 and each of theother gimbal portions 62 and 66.

The inner hinge unit 10 is shown assembled within the outer hinge unit40 in FIGS. 4 and 5, with the slot 14 in alignment with the slot 44, theslot 16 in alignment with the slot 46, the slot 24 in alignment with theslot 54, and the slot 26 in alignment with the slot 56. Since the gimbalportion 32 of the unit 10 is substantially coextensive with the gimbalportion 62 of the unit 40, the gimbal portion 34 is substantiallycoextensive with the gimbal portion 64, and the gimbal portion 36 issubstantially coextensive with the gimbal portion 66, three gimbalportions of double thickness are thus formed.

In manufacture, the hinge units 10 and 40 are machined to theirappropriate sizes and the various bores drilled therethrough. Then theinner hinge unit 10 is placed within the outer hinge unit 40 with theirbores in their proper position and the units are bonded together in aconventionalmanner such as by electron beam welding, cementing, etc.,along one or more circumferential joints. The slots 14 and 44 are thencut through the units 10 and 40, respectively, by a single cut and theremaining slots 16 and 46, 24 and 54, and 26 and 56 are cut in a similarmanner. For specific details of this manufacturing technique, referenceis made to application, Ser. No. 759,302 and Ser. No. 838,100 both byWillis B. Ensinger, and both assigned to the assignee of the presentinvention.

In the embodiment of FIGS. 6-10 an inner hinge unit and an outer hingeunit 140 are provided, which are similar in shape to the hinge units 10and 40, respectively, of the previous embodiment. A pair of generallyU-shaped, circumferential extending slots 14 and 16 are formed throughthe inner hinge unit 110, as better shown in FIG. 7, and an enlarged,radially extending bore, of a diameter exceeding the width of the slots,is formed at the ends of each slot. In particular, bores 114a and 114bare formed at the ends of the slot 114, and bores 116a and 1 16b areformed at the ends of the slot 116. The bores 114b and 116a are spacedapart slightly to form a necked-down flexure portion 118, and the bores116b and 114a are spaced slightly apart to form a necked-down flexureportion 120, the flexure portions 1 18 and 120 extending parallel to theaxis Z.

An additional pair of slots 124 and 126 are formed through the innerhinge member 110 in an axially spaced relation to the slots 1 14 and116. The slots 124 and 126 are also generally U-shaped, are invertedwith respect to the slots 114 and 116, and each has a bore formed at itsends. In particular, bores 124a and 124b are formed at the ends of theslot 124, while bores 126a and 126b are formed at the ends of the slot126. The bores 124b and 126a are spaced slightly apart to form anecked-down flexure portion 128, and the bores 126b and 124a are spacedslightly apart to form a neckeddown flexure portion 130. As in the caseof the flexure portions 1 18 and 120, the flexure portions 128 and 13extend parallel to the axis Z.

It is noted from an inspection of FIG. 7 that the flexure portions 118,120, and 130 are spaced at 90 intervals around the circumference of theinner hinge unit 110, with the slot 114 overlapping the flexure portion128, the slot 116 overlapping the flexure portion 130, the slot 124overlapping the flexure portion 120, and the slot 126 overlapping theflexure portion 1 18.

In this manner, three gimbal portions 132, 134 and 136 are formed asaresult of the above slots, with the flexure portions 118, 120, 128 and130 permitting flexing between the middle gimbal portion 134 withrespect to each of the other gimbal portions 132 and 136, whileproviding strength in the axial direction of the unit 1 10.

The outer hinge unit 140 is shown in FIGS. 6 and 8, and is similar tothe inner hinge unit 110 with the exception that the flexure portionsformed in connection with the former extend in a direction perpendicularto the axis Z. Particularly, a pair of slots 144 and 146 are providedthrough the wall of the unit 140, are generally U-shaped and have bores144a, 144b, and 146a, 146b,

respectively, formed at the ends thereof. The bores 144b and 146a arespaced apart in the axial direction of the unit to define a flexureportion 148, and the bores 146b and 144a are spaced apart in the samedirection to define a flexure portion 150.

An additional pair of slots 154 and 156 are formed through the hingeunit 140 and are axially spaced from the slots 144 and 146. These slotsare also generally U- shaped and are inverted with respect to the slots144 and 146. Bores 154a and 154b are formed at the ends of the slot 154,and bores 156a and l56b are formed at the ends of the slot 156, thebores 156a and 154b being spaced apart in the axial direction of theunit to define a flexure portion 158, and the bores 154a and 156b beingspaced apart in the same direction to define a flexure portion 160. Theflexure portions 148, 150, 158 and 160 thus extend in a directionperpendicular to the axis Z.

As in the case of the unit 110, the flexure portions 148, 150, 158, and160 are spaced apart at 90 intervals, and the slot 144 overlaps theflexure portion 158, the slot 146 overlaps the flexure portion 160, theslot 154 overlaps the flexure portion 150, and the slot 156 overlaps theflexure portion 148.

Three gimbal portions 162, 164 and 166 are formed by the slots 144, 146,154 and 156, and the flexure portions 148, 150, 158 and 160 permitrelative flexing movement between the middle gimbal portion 164 and eachof the other gimbal portions 162 and 166.

The inner hinge unit 110 is shown assembled within the outer hinge unit140 in FIGS. 9 and 10, with the slot 114 in alignment with the slot 144,the slot 1 16 in alignment with the slot 146, the slot 124 in alignmentwith the slot 154, and the slot 126 in alignment with the slot 156.Since the gimbal portion 132 of the unit 110 is substantiallycoextensive with the gimbal portion 162 of the unit 140, the gimbalportion 134 is substantially coextensive with the gimbal portion 164,and the gimbal portion 136 is substantially coextensive with the gimbalportion 166, three gimbal portions of double thickness are thus formed.

The assembly of FIGS. 6-10 is manufactured by a method described inconnection with FIG. 11 of the drawings. In particular, the tubularmembers 1 and 140, which have been previously ground and finished toform the various holes ther'ethrough, are telescoped one within theother and fixed together, as shown in FIG. 1 1. The telescoped tubularmembers 1 l0 and 140 are mounted with respect to a work bench or thelike and a base member 170 carrying a pair of tools 172 and 174 isadvanced relative to the tubular members in the direction indicated bythe arrows. The details of the work bench, the mounting assembly for thebase member, and the mechanism utilized to effect the above advancementis not shown in detail for the convenience of presentation.

The blades of each of the tools 172 and 174 extend in three planes asshown so that, upon passage of the tools through the tubular members 110and 140 corresponding cuts are made through the tubular members to formthe slots 114, 144 and 116, 146.

The base member 170, along with the tools 172 and 174, is then withdrawnand indexed 180 about the longitudinal axis of the base member so thatthe tools are turned upside down from the position of FIG. 11. The

telescoped tubular members 110 and 140 are indexed and the base member170 advanced towardsthe assembly in the foregoing manner, whereby theslots 124, 154 and 126, 156 are out.

It can be appreciated that this method of manufacture is extremelysimple since relatively complex slots are formed by using only twocutters making two separate passes through the assembly.

As mentioned earlier, the flexure hinge assembly of each of the aboveembodiments is adapted to serve as a connective and supportive linkbetween an inertial flywheel and a drive shaft therefor to form aneffective gyroscope. In particular, the drive shaft is directly coupledto one end of the assembly and the flywheel is connected to the otherend of the assembly, it being understood that these connections may bemade in any known manner such as by welding, bolting, etc.

In operation, rotation of the drive shaft will cause the entire assemblyto rotate about the axis 2, thereby transferring angular momentum to theflywheel. The assembly permits universal tilting of the flywheel aboutany transverse axis normal to the axis Z, while the flexure portions ofthe inner hinge units 10 and provide support in tension or compressionagainst all axial loads imposed on the flywheel. In a similar manner,the flexure portions of the outer hinge units 40 and provide support intension or compression against radial and/or torsional loads imposedupon the flywheel.

Of course, variations of the specific construction and arrangement ofthe assembly disclosed above can be made by those skilled in the artwithout departing from the invention as defined in the appended claims.

We claim:

1. A flexure hinge assembly comprising a pair of fixed telescopedtubular members, each said member having a longitudinal axis and a pairof transverse axes arranged in quadrature and intersecting at a commonpivot point, said corresponding axes of said members being aligned, saidpivot points of said members being coincident, each said member havingat least two pairs of slots extending through the wall thereof, theslots of one pair being axially spaced from the slots of the other pairto form at least three gimbal portions in each member, said gimbalportions including an upper gimbal portion and a lower gimbal portionand a middle gimbal portion, said middle gimbal portion connected tosaid upper and lower gimbal portions, a bore being formed through thewall of each of said members at each end of each of said slots, thebores at the ends of one slot of each pair of one of said membersterminating a predetermined circumferential distance from thecorresponding bores at the ends of the other slot of the same pair toform at least two flexure portions between said bores, said flexureportions extending parallel to the longitudinal axes of said members,the bores at the ends of one slot of each pair of the other of saidmembers terminating a predetermined axial distance from thecorresponding bores at the ends of the other slot of the same pair toform at least two additional flexure portions between said bores, saidadditional flexure po t ons extending perpendicular to said longitudinalaxes, wherein said middle gimbal portions of said members haverespective centers of gravity said centers of gravity being arranged tosubstantially coincide with each other and with said coincident pivotpoints.

between the other of said gimbal portions by means of said flexureportions.

5. The assembly of claim 1 wherein said flexure portions lie in a commonplane extending transverse to the axes of said members.

6. The flexure joint of claim 1 wherein the combined arcuate lengths ofthe slots of each pair along with their corresponding bores and flexureportions extend for substantially one circumference of their respectivetubular member.

1. A flexure hinge assembly comprising a pair of fixed telescopedtubular members, each said member having a longitudinal axis and a pairof transverse axes arranged in quadrature and intersecting at a commonpivot point, said corresponding axes of said members being aligned, saidpivot points of said members being coincident, each said member havingat least two pairs of slots extending through the wall thereof, theslots of one pair being axially spaced from the slots of the other pairto form at least three gimbal portions in each member, said gimbalportions including an upper gimbal portion and a lower gimbal portionand a middle gimbal portion, said middle gimbal portion connected tosaid upper and lower gimbal portions, a bore being formed through thewall of each of said members at each end of each of said slots, thebores at the ends of one slot of each pair of one of said membersterminating a predetermined circumferential distance from thecorresponding bores at the ends of the other slot of the same pair toform at least two flexure portions between said bores, said flexureportions extending parallel to the longitudinal axes of said members,the bores at the ends of one slot of each pair of the other of saidmembers terminating a predetermined axial distance from thecorresponding bores at the ends of the other slot of the same pair toform at least two additional flexure portions between said bores, saidadditional flexure portions extending perpendicular to said longitudinalaxes, wherein said middle gimbal portions of said members haverespective centers of gravity said centers of gravity being arranged tosubstantially coincide with each other and with said coincident pivotpoints.
 2. The assembly of claim 1 wherein each slot of one of saidmembers is aligned with a corresponding slot of the other member, andwherein each gimbal portion of one of said members is substantiallycoextensive with a gimbal portion of the other member.
 3. The assemblyof claim 2 wherein a portion of each flexure portion of one of saidmembers overlies a portion of a corresponding flexure portion of theother of said members.
 4. The assembly of claim 1 wherein one of saidgimbal portions of each of said members is connected between the otherof said gimbal portions by means of said flexure portions.
 5. Theassembly of claim 1 wherein said flexure portions lie in a common planeextending transverse to the axes of said members.
 6. The flexure jointof claim 1 wherein the combined arcuate lengths of the slots of eachpair along with their corresponding bores and flexure portions extendfor substantially one circumference of their respective tubular member.